I. Field of the Invention
The present invention relates to bows and crossbows and, in particular, to a mechanism for drawing back a bowstring.
II. Description of the Prior Art
Bows and crossbows are centuries old and in the case of crossbows have been made in the form of a shoulder-held or rifle-like weapon generally comprising a stock which includes a butt and a fore end portion, a resilient, flexible crosspiece called a bow prod which is supported at the forward end of the stock, a string whose opposite ends are attached to the corresponding opposite ends of the bow prod, and a releasable catch for holding the string at a position spaced rearwardly from the bow prod when the bow is cocked.
In conventional crossbows, when the string of the crossbow lies adjacent to the bow prod in what is called the rest or uncocked position of the string, there is little or no tension in the string and the bow prod is substantially unstressed. Crossbows are generally cocked by grasping the string with the hands and drawing the string along the fore end portion to a catch. When the bow is in the cocked position and the bow prod is bent, there is a large tension in the string. Because of this large tension in the bowstring, the bow may be difficult or impossible to operate for users who lack the necessary arm, hand and back muscle strength. Furthermore, as the surface area of the string over which the user can exert the necessary pressure is severely limited by the diameter of the string, some degree of pain may be inflicted on the user.
In the past, to enable crossbows to be cocked more easily, there have been provided for use with certain crossbows separate tools which have relatively movable parts engageable respectively with the stock and with the string. These tools can then be manipulated to move the string along the stock to the catch. Such tools may include a handle having an adequate surface area over which a user can apply the force necessary to cock the bow without suffering discomfort and the tool can be arranged to provide a mechanical advantage so that the force which is necessary for the user to apply to the tool can be less than the force which the tool applies to the string. The use of a separate tool for cocking a crossbow is inherently inconvenient as the tool must be carried in addition to the bow and bolts. Another method known to those skilled in the field of crossbows comprises those mechanisms in which a butt is pivotally connected to the fore end portion of the bow and is also connected with cocking means so that the butt of the crossbow may be used as a lever to cock the bow. Such arrangements, while commercially successful, are complicated in the design, expensive to manufacture and still require a considerable amount of physical strength to achieve cocking.